Essential oils are volatile oils obtained from plant or animal sources and are composed of complex mixtures of several constituents, such as monoterpenes and sesquiterpene hydrocarbons, monoterpene and sesquiterpene alcohols, esters, ethers, aldehydes, ketones, oxides and the like. These essential oils and their isolated constituents are frequently utilized as fragrance and flavor agents, and have been widely used in folk medicine for wound healing properties.
Scientific research has corroborated the beneficial effects of essential oils. Essential oils of eucalyptus have been found to “possess central and peripheral analgesic effects as well as neutrophil-dependent and independent anti-inflammatory activities” (Silva et al., 2003, J. Ethnopharmacol. 89(2-3); 277-283), and similar activity has been observed in essential oils from Lavendula angustifolia Mill. (Hajhashemi et al., 2003, J. Ethnopharmacol. 89(1):67-71). Essential oils have been demonstrated to exhibit antibacterial (Bozic et al., 2003, Phytother. Res. 17(9:1037-1040; Goren et al., 2003, Z. Naturforsch. 58(9-10):687-690; de Abreu Gonzaga et al., 2003, Planta Med. 69(8:773-775; Valero and Salmera, 2003, Int. J. Food Microbial. 85(1-2): 73-81) and antifungal (Paranagama et al., 2003, Lett. Appl. Microbiol. 37(0:86-90; Shin, 2003, Arch. Pharm. Res. 26(5):389-393; Velluti et al., 2003, Int. J. Food Microbiol. 89:145-154) activities. Virucidal activity of essential oils has also been observed, including direct virucidal effects against Herpes simplex viruses types 1 and 2 (Garcia et al., Phytother. Res. 17(9):1073-1075; Minami et al., 2003, Microbial Immunol. 47(a):681-684; Schuhmacher et al., 2003, Phytomedicine 10:504-510).
United States Patent Application Publication No. 20050048139 by Modak et al., published Mar. 3, 2005, relates to topical compositions comprising an emollient solvent and an essential oil, which may further comprise additional additives, among which citric acid, glycolic acid and lactic acid are cited.
United States Patent Application Publication No. 20050019431 by Modak et al., published Jan. 27, 2005, relates to compositions comprising a quaternary ammonium compound and an essential oil (or active component thereof).
A number of patent applications relate to compositions comprising an essential oil (or component thereof) where zinc salts are added to inhibit irritation associated with essential oils. Examples of such patent applications include United States Patent Application Publication No. 20040102429 by Modak et al., published May 27, 2004 and United States Patent Application Publication No. 20050238602 by Modak et al., published Oct. 27, 2005, now U.S. Pat. No. 7,435,429.
U.S. Pat. No. 6,858,317 by Aamodt et al., issued Feb. 22, 2005, relates to methods for protecting wood from mold and sap staining fungi which employ a non-toxic mold inhibitor which may be a plant extract such as an essential oil.
U.S. Pat. No. 5,100,652 by Kross et al., issued Mar. 31, 1992, relates to low concentration chlorous-acid generating oral hygiene compositions which may comprise an essential oil as a flavoring agent.
U.S. Pat. No. 5,310,546 by Douglas, issued May 10, 1994, relates to a mouth rinse preparation comprising hydrogen peroxide, zinc chloride, sodium citrate, sodium lauryl sulfate, citric acid and ethanol and optionally an essential oil which is a denaturing agent.
BiON offers several skin care products comprising citric acid, botanicals, and other agents for topical use (San Diego, Calif., US).
Johnson et al. (U.S. Pat. No. 6,319,958 and US20020165130) relates to the use of sesquiterpenoids to promote uptake of exogenous antimicrobial compounds. Similarly, a related article discloses the use of sesquiterpenoids, such as nerolidol, farnesol, bisabolol and apritone, in enhancing bacterial permeability and susceptibility to exogenous antimicrobial compounds, suggesting that sesquiterpenoids have a non-specific and general effect (Brehm-Stecher et al. 2003, Antimicrobial Agents and Chemotherapy, 47(10):3357-3360). In particular, Brehm-Stecher et al. report that nerolidol, farnesol, bisabolol and apritone enhanced the susceptibility of S. aureus to the antibiotics erythromycin, gentamicin, vancomycin, ciproflaxin, clindamycin, and tetracycline.
U.S. Pat. No. 4,867,898 by Spaulding et al., issued Sep. 19, 1989, relates to a liquid hard surface cleaner comprising pine oil and organic, oil-soluble acids at a pH from 0-6.
U.S. Pat. No. 6,753,305 by Raso and Caselli, issued Jun. 22, 2004, relates to a hard surface disinfectant comprising up to 20 percent of cinnamon oil or a component thereof, 0.01-5 percent of an organic acid, and optionally an additional essential oil.
International Patent Application Publication No. WO2007/077573 by Mukhopadhyay, published Jul. 12, 2007, relates to antimicrobial compositions comprising an antimicrobial agent, such as triclosan, and a functionalized hydrocarbon, where the functionalized hydrocarbon can be an essential oil, and/or a solvent.
Infection continues to be the major problem in the management of patients with burn wounds, decubitus ulcers and other surface infections. Control of skin infections is most important in preventing bacteremia and enhancing wound healing. Topical creams containing silver sulfadiazine and other topical antimicrobial agents have been developed and widely used for such purposes. However, complete control of target infection has not been achieved with the use of these agents.
1% silver sulfadiazine (Silvadene®) cream has been effectively used as a prophylactic cream to control burn wound infections. However, it is not very effective in treating established deep wound infections due to the drug's failure to penetrate the wound eschar. The incidence of wound colonization with S. aureus or C. albicans in Silvadene® treated patients has spurred research for other agents.
It has been well established that continuous control of infection facilitates rapid healing of partial thickness burns, decubitus ulcers and other types of surgical wounds and facilitates their closure. Wound healing, especially in burns, is a complex process for which zinc has been found essential. Studies on zinc have shown beneficial results in wound healing with acceleration of the re-epithelialization process and an antibacterial effect. Zinc oxide has been reported to activate endogenous zinc-dependent matrix metalloproteinases, augment expression of endogenous growth factors and facilitate keratinocyte migration.
In earlier studies, topical treatment of burn wounds with zinc sulfadiazine was found to accelerate wound healing better than treatment with silver sulfadiazine. (Gyn and Obstet, 142:553-559 (1976)).
To prevent or reduce infection of burn wounds, topical ointments have been used. These ointments have incorporated silver sulfadiazine (U.S. Pat. No. 3,761,590, incorporated herein by reference) or various antibiotics. A topical ointment for burns has also been reported which contains a combination of silver salts and norfloxocin, a quinoline antibiotic, or its salts (U.S. Pat. No. 4,404,197, incorporated hereby by reference). In the case where the antibiotic is silver norfloxocin, U.S. Pat. No. 4,404,197 reports a synergistic enhancement of activity. U.S. Pat. No. 5,374,432 relates to topical anti-infective ointments containing an antibiotic, silver salt, and sterile carrier. These compositions were found to not only provide improved antimicrobial efficacy, but also reduced incidence of microbial resistance.
U.S. Pat. No. 6,987,133 relates to a topical preparation containing silver sulfadiazine dispersed or solubilized in a cream or lotion base matrix which can be sprayed directly on the burn wound. European Patent No. EP0653214 relates to a topical antibacterial preparation containing silver sulfadiazine and collagen for the treatment of infected hands and for the advancement of their healing.
There is a continuing desire for an antimicrobial or wound healing composition that are non-irritating, safe, and effective for repeated use in various professional and non-professional settings.